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    <title>ShellCheck: SC2050 – This expression is constant. Did you forget the `$` on a variable?</title>
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    <h1>SC2050 – ShellCheck Wiki</h1>
    <a href="https://github.com/koalaman/shellcheck/wiki/SC2050">See this page on GitHub</a>
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    <h2
id="this-expression-is-constant-did-you-forget-the--on-a-variable">This
expression is constant. Did you forget the <code>$</code> on a
variable?</h2>
<h3 id="problematic-code">Problematic code:</h3>
<div class="sourceCode" id="cb1"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb1-1"><a href="SC2050.html#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> <span class="bu">[</span> myvar <span class="ot">=</span> <span class="st">&quot;test&quot;</span> <span class="bu">]</span></span>
<span id="cb1-2"><a href="SC2050.html#cb1-2" aria-hidden="true" tabindex="-1"></a><span class="cf">then</span></span>
<span id="cb1-3"><a href="SC2050.html#cb1-3" aria-hidden="true" tabindex="-1"></a>  <span class="bu">echo</span> <span class="st">&quot;Test mode&quot;</span></span>
<span id="cb1-4"><a href="SC2050.html#cb1-4" aria-hidden="true" tabindex="-1"></a><span class="cf">fi</span></span></code></pre></div>
<h3 id="correct-code">Correct code:</h3>
<div class="sourceCode" id="cb2"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb2-1"><a href="SC2050.html#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> <span class="bu">[</span> <span class="st">&quot;</span><span class="va">$myvar</span><span class="st">&quot;</span> <span class="ot">=</span> <span class="st">&quot;test&quot;</span> <span class="bu">]</span></span>
<span id="cb2-2"><a href="SC2050.html#cb2-2" aria-hidden="true" tabindex="-1"></a><span class="cf">then</span></span>
<span id="cb2-3"><a href="SC2050.html#cb2-3" aria-hidden="true" tabindex="-1"></a>  <span class="bu">echo</span> <span class="st">&quot;Test mode&quot;</span></span>
<span id="cb2-4"><a href="SC2050.html#cb2-4" aria-hidden="true" tabindex="-1"></a><span class="cf">fi</span></span></code></pre></div>
<h3 id="rationale">Rationale:</h3>
<p>ShellCheck has found a <code>[ .. ]</code> or <code>[[ .. ]]</code>
comparison that only involves literal strings. The intention was
probably to check a variable or command output instead.</p>
<p>This is usually due to missing <code>$</code> or bad quoting:</p>
<pre><code>if [[ &quot;myvar&quot; = &quot;test&quot; ]]             # always false because myvar is a literal string
if [[ &quot;$myvar&quot; = &quot;test&quot; ]]            # correctly compares a variable

if [ &#39;grep -c foo bar&#39; -ge 10 ]       # always false because grep doesn&#39;t run
if [ &quot;$(grep -c foo bar)&quot; -ge 10 ]    # correctly checks grep output</code></pre>
<h3 id="exceptions">Exceptions:</h3>
<p>None</p>
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